A large bird is perched on a tree branch at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013. Beginning next month, several hundred aging and diseased trees will be cut down and replaced with younger ones. less

A large bird is perched on a tree branch at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013. Beginning next month, several hundred aging and diseased trees will be cut down and replaced ... more

Photo: Paul Chinn, The Chronicle

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A woman walks through a grove in Golden Gate Park. Some of its trees are scheduled to be cut down.

A woman walks through a grove in Golden Gate Park. Some of its trees are scheduled to be cut down.

Photo: Paul Chinn, The Chronicle

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A large branch from a Monterey pine rests near Martin Luther King Jr. Drive.

A large branch from a Monterey pine rests near Martin Luther King Jr. Drive.

Photo: Paul Chinn, The Chronicle

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Arborist Larry Costello and project manager Melinda Stockmann view a poster designed to educate park employees about diseased trees at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013. Beginning next month, several hundred aging and diseased trees will be cut down and replaced with younger ones. less

Arborist Larry Costello examines a graph representing the density of an aging Montery pine tree marked for removal after boring a tiny hole into its trunk at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013. Beginning next month, several hundred aging and diseased trees will be cut down and replaced with younger ones. less

Arborist Larry Costello examines a graph representing the density of an aging Montery pine tree marked for removal after boring a tiny hole into its trunk at Golden Gate Park in San Francisco, Calif. on ... more

Photo: Paul Chinn, The Chronicle

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Arborist Larry Costello examines a crack in an aging tree that is marked for removal at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013.

Arborist Larry Costello examines a crack in an aging tree that is marked for removal at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013.

Photo: Paul Chinn, The Chronicle

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A sign is posted on a Monterey pine tree designated for removal at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013.

A sign is posted on a Monterey pine tree designated for removal at Golden Gate Park in San Francisco, Calif. on Thursday, Feb. 14, 2013.

Photo: Paul Chinn, The Chronicle

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Golden Gate Park's aging trees to fall

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The hulking trees were planted nearly 100 years ago, before Alexander Graham Bell called San Francisco for the first time from his New York office. Before City Hall was opened a second time. Before blueprints for the Golden Gate Bridge were even drawn up.

But over the next few months, city park workers will fell almost 150 Monterey pine, cypress and eucalyptus trees in Golden Gate Park. The trees, most of which are 80 to 100 years old, are unhealthy, dead or a risk to the 13 million people who visit the 1,017-acre park each year, parks officials said.

"The focus is trees that would possibly go over the road or a main pathway" if they toppled over, said Larry Costello, a tree consultant hired by the city's Recreation and Park Department. "Wherever trees and people are in close proximity, there's a reason to be concerned."

Falling trees or tree limbs on city park property have damaged 61 cars since 2008. Three people were injured in 2012 when a tree branch fell on them. A fourth person was knocked in the head in 2009, and a woman died in 2008 when a Stern Grove tree branch fell on her car, crushing her as she was loading her dog into her Subaru.

Bond OKd for tree care

Voters approved a bond in 2008 that included $4 million to care for the roughly 130,000 trees spread across city parks. A large focus of the program has been Golden Gate Park's 25,000 trees.

Since 2011, city contractors have examined 3,000 of the park's trees and found that almost 360 must be cut down. More than 200 already have been sent to the chipper, and all of them will be replaced, said Melinda Stockmann, a park department project manager. The entire process for analyzing and removing the park's trees is about $1.7 million.

Some of the trees are clearly dead or dying. They bear naked, brown branches and lean far to one side.

"They're going to say, the light is better over here, so I am going to grow over here," Costello said, pointing to a crooked Monterey pine tagged for removal. "But once they lean too far over, they aren't stable."

But other trees look healthy, until Costello examines them.

"You see this crack here?" Costello said, pointing at the 40-inch trunk of a towering 80-foot pine tree near 34th Avenue and Martin Luther King Drive. "That shows me that there is stress on the tree, that it is not stable. That's an indicator that this thing is starting to fail."

Sometime over the next month, a contract tree crew will come out and, piece by piece, cut down that tree and dozens of others. Eventually, replacement saplings will be planted in another part of the park, Costello said.

Check for bird nests

But before the tree is torn down, wildlife biologists will search the branches for any nesting birds. If a bird is spotted, the tree will stand until the nesting season is over, Costello said.

"When we're out there and we spot a nest, it's 'OK, let's not work here now, let's do that work later on,' " Costello said.

Nearby residents, who hate to see any tree torn down, often tell the workers they're upset to see the tree go, said Dennis Kern, the park department's director of operations.

"People love their trees and we love them, but we love them and want them to be healthy. We never capriciously take out a tree because we feel like it," he said.

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